Lamp construction comprising a reflector



Dec. l2, 1939. F. l.. G. SCHNEIDER 2,183,048

LAMP CONSTRUCTION COMPRISING A REFLECTOR Filed Dec. v15, 1958 2 sheets-sheet 1 INVEA/Y'OR .F L. G. JCHNEIDER AWR/w57 Y DW' 12; 1939. F. l.. G. SCHNEIDER 2,183,048

y LAMPl CONSTRUCTION COMPRISING A REFLEGTOR Filed Dec. 13, 1938 2 SheebS-Sheel'l 2 BY @Ma/'nq ATTORNEY Patented Dee. 12, 1939 UNITED STATES PATENT oi-llca Lm CONSTRUCTION COMPRISING A FLECT R.

the Netherlands application December 1s, 193s, serial No. 245,319 In' the Netherlands January 28, 1937 ,5 Claims.

The invention relates to a lamp comprising a reector. With the existing devices of this kind for lighting streets, locks, canals, railway stations and the 6' like a portion of the lamp which is directly illuminated by the source of light will still be visible, theoretically speaking at an infinite and practically speaking at a very great distance.

With lighted road, for example, where lamp l posts are generally placed at approximately uniform distances, a person travelling along such a road will see a portion of the illuminated inner surfaces of the said lamps projected in the shape' of oval, rectangular, or otherwise shaped discs,

a u depending on the form of theI devices.

Since the lighting of these portions is very intensive on account of their close proximity to the source of light, the attention of the travellers along such roads is turned away from the less 20 brightly lighted objects on the said road. Moreover the projections will produce a more or less troublesome blinding effect on the observer. 'This evil is even more strongly felt in the case of lighted railway platforms where the signal 25 lights arranged between those lighting devices 4are often only faintly perceptible.

, In general, however, an object even if it is less brightly lighted will be plainly visible, as long as the eye is not struck directly by rays of 30 light.

The object of the present invention is to produce a lamp structure for the above purposes in which the portions of the lamp which are illumined by the source of light-during the time V36 that the observer remains outside the cone of light rays formed by the lamp-will be invisible or practically invisible to the observer either from all sides or from some sides, so that the blinding eiect will be eliminated.

40 According to the invention the drawback mentioned above is overcome by providing below the lower edge of the reector and outside the cone proper of the projected light beam, screens of the 'type of Venetian blinds positioned horizon- 45 tally or more or less inclined in such a way that for an observer remaining at a distance outside the cone of the light beam the top portion ofthe screens is invisible. In this manner a person will only observe the underside of the screens 55 If the screens are placed -horizontally they may be so wide that they will screen oi practically all of the illuminated inner surface of the reflector which is turned towards the observer, so that only at a very great distance a small portion thereof will be visible between the screens. 5

The width of the screensv may, however, be greatly reduced by surrounding the screens at the outer side by a wall which forms a continuation of the reflector casing. This wall partially provides the screening and prevents a portion of the inner wall from being visible between the screens, without unduly increasing the dimensions of the lamp structure. At the same time the screens are connected with each other and with the reflector casing in a very simple manner.

It is also possible to produce complete screening without the aid of such casing by arranging the screens in a more or less inclined" position in such a way that for an observer remaining at some distance outside the cone of the projected light beam the reflector opening is quite invisible.

Another embodiment of the invention is still possible in which each screen is formed by two walls situated one above the other, the edges of the walls being connected with each other at the inner side of the lamp structure, whereas starting from that connected edge, the lower wall is inclined downwardly and the upper one 30.

.thereabove The invention is further explained by the accompanying drawings in which different embodlments are illustrated by way of example Iand in which:

Fig, 1 is a schematica] view of a known' road lighting system. f"

Fig.r 2 is a lighting vdevice belonging to the 40 road lighting system according to Fig. 1, on an" enlargedscale.

Fig. 3 is a section through one half of a lamp construction vaccording to the invention.

Fig. 4 is a section through one half of a sec- 45 ond embodiment of a lamp construction.

Fig. 5 is a section through one half of a third embodiment of a lamp construction.

Fig. 6 is a section through one half of a fourth embodiment of a lamp construction.

Fig. 7 -is a'section through one half of a fifth embodiment of a lamp construction.

In the road lighting system according to Fig. 1 it is assumed that the eye 0 of the observer is positioned at a distance -of 30 vmetres from the 55 The observe'r therefore at this distance will beV far outside the cone of light, but nevertheless he will see the lamp very clearly, because of the fact that the pencil of light rays'located between the rays G I and 0 2 will reach his eye and will cause him to see clearly the projection of the plane i-2 of the lamp structure shown on an enlarged scale in Fig. 2, which projection will be the surface 2 3 having the shape of an ellipse with the axes I 2 and 2 3. It may be considered to be known that the lighted surface will produce on the observer the blinding effect described above.

In order to render the planes I 2 or 2 3 respectively invisible to the observer, it would be necessary to arrange about the entire lamp structure a screen 2 4 5, Fig. 3, whereby the interior surface would be screened off for an observer whose eye is situated at the point 0'. The interior surface of the screen shou`.d then be light-absorbent, so that it cannot emit any light towards the observer, since otherwise the observer would still see the projection of plane 4 5. With the means now available this object cannot be realized, since up to the present there are no materials for making the surface I 2-4-5 so as to even approximately meet the above requirements. 'i

'I'he object of the present invention is to absorb the rays of light striking the imaginary plane I 2 4 5 illustrated in Fig. 3, for example by intercepting them in such a way that they do not reach the observer.

A construction by means of which this is obtained according to the invention is illustrated in Fig. 3 taking as a starting point the case illustrated in Fig. 1, with this difference that the observer who has advanced until he is at a distance of 20 metres from the axis of the lamp, will be unable to see the plane I 2, and only when further approaching the axis of the lighting device will begin to see the surface I 2 in part. To this effect, it is necessary that all rays of light striking the surface of the cone l 2 4 5 are absorbed so that they cannot reach the observer who advanced to a distance of 20 metres.

The lamp construction which is planned in the shape of a solid of revolution consists of a casing 6 either provided at its inner side with a refiector, or having an interior wall which is more or less light-reflecting, the opening of the casing being denoted by the reference numerals I Z, as in Figs. 1 and 2. At the lower edge of the reflector case is provided a shield or screen forming a continuation of the casing and consisting of a horizontal annular portion 1 and a conical portion 8 having an opening 9 I8. AOn the inside of wall 8 horizontal annular screens II, I2, I3 and I4 are arranged in the manner of Venetian blinds, the internal diameters of which are denoted by III-H2, l2I-I22, I3I-I32 and I4I I42, while the external diameters are denoted by II3-II4, I23I24, I33-I34 and |43- I44. The internal diameters, III I|2, I 2I I22,

lli-|32 and |4I-l42-c0inclde with the cirarcanes cumierence of the cone of light rays 5 I-2 i. The screens are located outside the cone of light and consequently do not obstruct the free radlation of the lamp.

The number of screens il, i2, I3 and i4 inthe embodiment illustrated is reduced to a minimum, but this number may also be greater. All rays 4of light emitted outside' the cone of light rays proper, and which intersect the plane 5--I 2 4, will either strike the upper side of the screens II, I2., IS and i4 or the interior wall oi' the screen but this will occur at places which are not visible to the observer as they are shielded by the screens II, i2, I8 or I4.

The mutual distance of the screens must be chosen with a view to the said considerations.

Infthe example illustrated in Fig. 3 the place where the lowermost screen is to be located may be found by determining the intersection point of line 9 2 (the direction of which is to corre.- spond to the light ray II' 2 in Fig. 1 in which the observer is supposed to have advanced to a distance of 20 metres) with line I-5, that is to say with the cone surface 5-i2 4. In this point the lowermost screen I4 has been arranged, thus preventing the observer from seeing the surface I 2. On account of screen I4 the portion of screen 8 located below screen I4 may be deleted. When drawing a line through the points 9 and |42 intersecting the inner surface of the screen 8 at the point I5, it will be clear that the small cone surface with the generatrx I4- I44, even when it is lighted, will remain invisible to the observer.

If now the point I5 is connected with the point I, the point of intersection |32 with the line 2 4 will determine the place where another screen is to be provided. If the point 8 is then connected with the point |32, it will be found that tne small cone surface IG-I34 is invisible. ing in this manner the screens which are indispensable will be determined while it will be appreciated that the cone surfaces having the generatrices I34 I5, l24 I6, etc. which are located in the shadow of the adjoining screen will not be lighted and consequently will be invisible.

In this manner all the rays of light intersecting the cone surface 5 I 2 4 will be absorbed so that the said surface as a whole is invisible for the observer.

It is evident that the internal diameters of the screens II, I2, I3, I4 need not coincide with the circumference of the cone of light. It is only required that these interior diameters are located outside the cone of light, that the upper sides of the screens are `not visible to the observer and that in the embodiment described above the lighted portions of the screen 8 are also shielded by the screens Il, i2, I3 and I4.

An embodiment in which the interior edges of the screens are located, outside the cone of light is illustrated in Fig. 4, which embodiment otherwise is similar to that of Fig. 3.

Fig. 5 represents an embodiment of a lamp construction in which screen 8 has been omitted and screens Il, I2, I3, I4 are so wide that only a very small portion of the reflector opening I Z will be visible between them for a person positioned at a very great distance from the lamp, which ln actual practice is more than sufilcient.

Even this possibility may be obviated by arranglng the screens l I, l2, I3 and I4 in a more or less inclined position, as indicated in Fig. 6. In this embodiment as in the embodiments according to Figs.' 4 and 5 described above, vthe Continu-- interior circumferences of screens II, I2, I3 and I 4 are determined as described -for the construction according to Fig, 3. It is evident from Fig. 6 that the reflector opening will be invisible at any distance outside a cone of light the generatrix of which is indicated by 2-I4I'9 or by I-I42-IIL Fig. 7 represents another embodiment in which the screens II, I2, I3 and I4 are ,formed by V- shaped walls, which construction may be obtained by providing in an embodiment according to Fig. 6 a wall between each inner edge of one of the screens II, I2, I3 and I4 and the outer edge of a screen located thereabove. In this manner a very well connected whole is obtained.

With the embodiments omitting screen 8 according to Figs. 5 and 6 the screens II, I2, I3 and Il may be connected with each other in any manner desired.

It is still to be observed that the screens 1, 8,

II, I2, I3 and I4 need not surround the entire circumference of the lamp construction.

By way of example, it is possible to omit the screens completely or partially at those sides 5 where the radiation of the light will not cause trouble or is even expressly desired, as for instance when a road is lighted at one side or at both sides. The same will contingently be true for the reflector.

In general the eiiicacy of the lamp will be i'ncreased by giving a suitable color to the entire construction, whereby moreover the danger of illumination by means of the reflection caused by objects which may be present in the vicinity of the lamp, will be reduced.

It is furthermore to be borne in mind that the construction according to the invention may also be applied to existing lamps.

I claim:

1. As a new article of manufacture, a ilood light comprising in combination, a reflector for projecting a diverging light b eam 'of predetermined shape, said reilector also projecting undesired stray light, a plurality of substantially plane opaque screens having openings of geometrical conguration similar to the reflecting area of said reflector, said screens spacedly arranged from each other and said reflector and in front of and in alignment with the latter, the areas of the openings of said screens exceeding said reecting area and increasing about proportional to the square of their distance from said reflector so as to closely embrace said projected diverging light beam and to intercept undesired stray light projected by said reilector.

2. As a new article of manufacture, a ood llglit comprising, in combination, la reflector for projecting a diverging light beam of predetermined shape, said reflector also projecting undesired stray light. a plurality 'of substantially plane opaque screens having openings of geometrical coniiguratlon similar Ato the reflecting area of said reileotor, said screens spacedly arranged from eachother and said reilector and in front of and lnalignmentwiththelattenthelrea'lofth openings of said screens exceeding said reflecting area and increasing about proportional to the square of their distance from said reilector, said screens extending substantially vertically to the main direction of said beam so as to intercept stray light which would otherwise strike an observer within a predetermined distance outside said shaped beam.

3. As a new article of manufacture, a flood light comprising, in combination, a substantially circular reflector for projecting a conically diverging light beam of predetermined angle, said reilector also projecting undesired 'stray light, a plurality of substantially plane opaque and substantially annular screens spacedly arranged from each other and in front of said reilector, the substantially circular openings of said screens in alignment with the reiiectinglarea of said reilector and their areas increasing about proportional to the square of their distance from said reflector, the number and width of said screens and their spacing chosen so as to intercept-undesired stray light projected by said reector within a conus'the angle of which substantially exceeds that of said projected beam.

4. As a new article of manufacture, a ood light comprising, in combination, a reiiector for projecting a diverging light beam of predetermined shape, said refiector also projecting undesired stray light, an outwardly extending substantially annular opaque wall in front of said reflector, a plurality of substantially annular opaque screens spacedly arranged from each other and said reector inside of and associated with said wall, said screens extending substantially vertically to the main direction of said beam, the interior opening of saidl annular wall at least equaling and the openings of said screens exceeding the reilecting area of said reector so as to closely embrace said projected light beam and to intercept undesired stray light projected by said reflector which would otherwise strike an observer within a predetermined distance outside said shaped beam.

5. As' a new article of manufacture, a flood light comprising, inrcombination, a reflector for projecting a diverging light beam of predetermined shape, said reector also projecting undesired stray light, a plurality of opaque screens having openings of substantially plane geometrical conguration similar to the reecting area of said reiiector, the areas of said openings exceeding said reflecting area and increasing about proportional to the square of their distance from said reflector, said screens arranged in juxtaposed lposition and outwardly staggered relation and in 

